Modelling with AutoCAD 2011 Part 9 pps

6 Select the COPY FACES icon from the Solids Editing toolbar and:prompt Select faces respond pick face 2 then right-click/enter prompt Specify a base point or displacement respond Endpoi

6 Select the COPY FACES icon from the Solids Editing toolbar and:

prompt Select faces

respond pick face 2 then right-click/enter

prompt Specify a base point or displacement

respond Endpoint icon and pick pt3

prompt Specify a second point of displacement

enter @50,0,100 <R> then exit the command

7 The selected face is copied as fig(d)

8 Erase all objects from the screen and create two primitives:

a) cylinder: centre 0,0,0; radius: 30; height: 100

b) cone: centre: 0,0,200; radius: 100; height: –150

c) union the cone and cylinder – fig(e)

9 Select the SHELL icon from the Solids Editing toolbar and:

prompt Select a 3D solid

respond pick any point on the composite then right-click/enter

prompt Enter the shell offset distance

enter 10<R> then X<R> and X<R>

10 The cylinder/cone is offset by 10 in ‘all directions’ – fig(f)

11 Hide the model then regen

12 With the EXTRUDE FACES icon:

a) pick any point on the ‘top face’

b) extrusion height: –10

c) angle of taper: 0 – fig(g)

13 Repeat the extrude faces command and:

a) pick any point 4 on the ‘new rim’ of the composite

b) extrusion height: 50

c) angle of taper: 5 – fig(h)

This completes the third solids editing example

Other solids editing options

Not all of the solids editing options have been used in the worked examples The

following is a brief description of those not considered:

a) Clean: removes all redundant edges and vertices, e.g imprinted edges

b) Separate: separates 3D solid objects with disjointed volumes into independent 3D

objects It DOES NOT separate composites created by Boolean operations into the

original primitives

c) Check: confirms that a selected object is a valid ACIS solid

d) Color Edges/Faces: a very useful option as it allows individual edges and faces to be

coloured, i.e a cube could be created on layer MODEL (red) and the six faces of thecube assigned different colours

e) Copy Edges/Faces: should be obvious

f) Delete faces: allows faces of a model to be deleted, but the option has obvious

limitations Useful with fillet/chamfer edges

Solids editing 233

Solids editing errors

When a solids editing option is activated and completed, the command line will display:

a) Solid validation started

b) Solid validation completed

Solids editing may not always work due to the model selected or the option which hasbeen activated Errors which are displayed include:

1 No solution for an edge

2 No solution for a vertex

3 No loop through new edges and vertices

4 Could not taper surface as requested

5 Improper edge/edge intersection

6 Gap cannot be filled

If and error message is obtained, then the active option cannot be performed on theselected object Try again

Summary

1 Solids editing allows the user several options

2 These options can result in very interesting and complex models which may be difficult

to achieve from basic primitives

3 The solids editing options are divided into four categories:

A region is a closed 2D shape created from lines, circles, arcs, polylines, splines, etc and

can be used with the extrude and revolve command to create solid composites When

created, a region has certain characteristics:

• it is a solid of zero thickness

• it is coplaner, i.e must be created on the one plane

• it consists of loops – outer and inner

• the loops must be continuous closed shapes

• every region has one outer loop

• there may be several inner loops

• inner loops must be in the same plane as the outer loop

• regions can be created with the BOUNDARY command

• regions can be used with the solid EXTRUDE and REVOLVE command

Regions allow the user another method for creating solid models and very complex

models can be created with regions They can also be used be apply hatching to models

and extract details from models

Example 1 – a splined shaft

1 Open your A3SOL template file as normal and display suitable toolbars

2 Refer to Fig 36.1 (which only displays the 3D viewport) and create the layout from three

circles having diameters 120, 40 and 16 The actual layout is your design but use the 0,0

point as indicated

3 Zoom centre about 0,0,40 at 200 magnification – all viewports

4 Select the SUBTRACTION icon from the Solids Editing toolbar, pick the largest circle

then right-click and:

prompt No solids or regions selected

5 Select the REGION icon from the Draw toolbar and:

prompt Select objects

respond pick all circles then right-click

prompt 13 loops extracted

13 Regions created

Chapter 36

6 Menu bar with Modify-Solids Editing-Subtract and:

prompt Select solids or regions to subtract from

Select objects

respond pick the largest circle then right-click

prompt Select solids or regions to subtract

Select objects

respond pick the 12 smaller circles then right-click

and the region is created as fig(a)

7 At this stage save as MODR2002\REGEX for the next exercise

8 With the lower left viewport active select the EXTRUDE icon from the Solids toolbar and:

a) objects: pick the region

b) height: 100

c) taper angle: 0 – fig(b)

d) hide and shade

9 Undo the hide, shade and extrusion effects, then use the EXTRUDE icon with thefollowing entries:

i) height: 100, taper angle: 3 – fig(c) Undo effect

ii) height: 100, taper angle: –3 – fig(d)

10 This exercise does not need to be saved

Figure 36.1 Region example 1 – an extruded component.

Example 2 – a revolved component

1 Open drawing file MODR2002\REGEX saved from the previous exercise with UCS BASE

as Fig 36.2(a)

2 Menu bar with Tools-New UCS-Origin and:

prompt Origin point<0,0,0>

enter –100,–100,0 <R>

3 Zoom centre about 150,0,0 at 250 magnification

4 Select the REVOLVE icon from the Solids toolbar and:

prompt Select objects

respond pick the region then right-click

prompt Specify start point for axis of revolution o r define axis by

enter X <R> – the X axis option

prompt Specify angle of revolution

enter –90 <R>

then pan model to suit and hide – fig(b)

5 Undo the hide and revolve effect to leave the original region

6 Using the REVOLVE icon:

a) pick the region then right-click

b) enter Y as the axis if revolution

c) enter 180 as the angle

d) pan and hide – fig(c)

e) undo the hide and revolve effect

Regions 237

Figure 36.2 Region example 2 – a revolved component.

7 Draw a line from: 0,0,0 to: @0,0,100

8 Menu bar with Modify-3D Operation-Rotate 3D and:

a) pick the region then right-click

b) enter X <R> as the axis

c) enter 100,100,0 as a point on the axis

d) enter 90 as the rotation angle

9 With the REVOLVE icon:

a) pick the rotated region the right-click

b) enter O <R> – object option

c) pick lower end of vertical line

d) enter 240 as the angle of revolution

e) pan to suit then hide – fig(d)

10 This completes the second exercise Save if required

Example 3 – using a boundary

1 Open your A3SOL template file as normal and refer to Fig 36.3

2 Draw three circles:

a) centre: 50,0, radius: 50

b) centre: 0,50, radius: 60

c) centre: 75,75, radius: 75

4 Make a new layer: BND, colour blue and current

5 Zoom centre about 50,50,50 at 200 magnification

Figure 36.3 Region example 3 – created from a boundary.

6 Menu bar with Draw-Boundary and:

prompt Boundary Creation dialogue box – Fig 36.4

respond 1 pick Object type: Region

2 pick Pick Points

prompt Select internal point

respond pick a point indicated in Fig 36.3

prompt Selecting everything

Selecting everything visible

Analyzing the selected dataAnalyzing internal islands

then Select internal point

respond right-click

prompt 1 loop extracted

1 Region createdBOUNDARY created 1 region

7 Erase the three circles to leave the blue region – fig(a)

8 Using the EXTRUDE icon:

a) pick the blue boundary region then right-click

b) enter a height of 125

c) enter a taper angle of 2

d) hide the model – fig(b)

9 Undo the hide and extrude effects to leave the blue region

10 With the REVOLVE icon:

a) select the blue region then right-click

b) enter Y as the axis of revolution

c) enter 270 as the angle of revolution

d) hide – fig(c)

11 Undo the hide and revolve effect

12 Restore UCS FRONT, and with layer MODEL current draw a polyline with:

start point: 0,0

next point: @0,100

next point: arc option with endpoint: @–200,0

next point: arc endpoint: @120,0

next point: arc endpoint: @–60,0 then right-click

Regions 239

Figure 36.4 The Boundary Creation dialogue box.

13 Restore UCS BASE and make layer BND current

14 With the EXTRUDE icon:

a) select the blue region

b) enter P <R> for the path option

c) pick the red polyline

d) pan to suit

d) hide to give fig(d)

15 The exercise is complete, save?

16 Note

Although this exercise has been completed using the Boundary command, it could havealso been completed by making the three circles into regions and then using the Booleanintersection command

Summary

1 A region is created from closed shapes, e.g polylines, arcs, circles, ellipses etc

2 Regions can be created with the BOUNDARY command

3 Regions consist of loops and all regions must have an outer loop There can be severalinner loops

4 Regions can be extruded and revolved

5 All parts of a region are extruded/revolved to the same height or angle

6 Regions are extruded along the Z-axis of the current UCS The height of the extrusioncan be positive or negative

7 Regions can be extruded along a path

Assignment

This activity requires a region to be created from circles, copied, scaled and then extruded

to different heights

ACTIVITY 21: Ratchet mechanism of Macfaramus

While digging in a water bed outside the city of CADOPOLIS, a device was discoveredwhich was thought to be a ratchet mechanism for a primitive type of waterwheel Thismechanism has three distinct ‘parts’ to it, each having the same shape

Using the reference sizes given, create the outline from circles, convert these circles intoregions, then subtract the smaller circles from the larger The other parts of themechanism are scaled by 0.85 and 0.55 from the original When the three parts havebeen created, they have to be:

a) lower part: extruded to a height of –50 with –15 taper

b )middle part: extruded to a height of 60 with 0 taper

c)top part: revolved about an line object for –90 degrees and then array for 3 items about

the top ‘circle’ centre The line for the object can be drawn at your discretion The line

I used is indicated in the activity drawing

Notes:

1 Use a 0,0 centre point for the large circle and for copying and scaling purposes

2 Each scaled part is positioned on top of the previous part

3 Use your discretion for sizes not given

Inquiring into models

In this chapter we will create two new composites and then use the AutoCAD inquiry

commands to determine the properties of these solids We will also investigate how to

create a material properties file

Composite model 4 – a slip block

1 Open the A3SOL template file with normal settings, display the Inquiry toolbar and refer

colour: red colour: blue

3 Centre the model about 80,50,50 at 200 magnification

Chapter 37

Figure 37.1 Composite model 4 – a slip block (plotted without hide).

4 Create two green cylindrical primitives with:

a) centre: 60,0,50

radius: 25centre of other end option: @0,100

b) elliptical option

centre of ellipse: 0,50,50axis endpoint: @20,0length of other axis: @0,0,30centre of other end: @180,0

5 a) union the red box and blue wedge

b) subtract the two green cylinders from the composite

c) note the ‘curves of interpenetration’

d) shade and note the colour effect

e) use the 3D orbit command with the model, then restore the original 2D wireframe

representation

6 At this stage save the composite as MODR2002\SLIPBL

7 Select the AREA icon from the Inquiry toolbar and:

prompt Specify first corner point or [Object/Add/Subtract]

enter O <R> – the object option

prompt Select objects

respond pick the composite

prompt Area = 98062.84, Perimeter = 0.00

9 The area value displayed is the surface area of the composite in square units (mm?) Asolid object has no perimeter, hence the 0 value

9 Select the REGION/MASS PROPERTIES icon from the Inquiry toolbar and:

prompt Select objects

respond pick the composite then right-click

prompt AutoCAD Text Window

with details about the model including:

Mass = 995882.69Volume = 995882.69

prompt Write analysis to a file?<N>

enter Y <R>

prompt Create Mass and Area Properties File dialogue box

respond 1 check – Save in: named folder active

2 check – Save as type *.mpr – materials properties

3 enter File name: SLIPBL

4 pick Save (more on properties file later)

10 Note that the mass and volume values are the same as AutoCAD 2002 assumes a density

of 1

Composite model 5 – a casting block

1 Close and existing drawings then open A3SOL template file with the normal settings and:

a) refer to Fig 37.2

b) zoom centre about 37,50,18 at 150 magnification in all viewports

2 With the 3D viewport active, create a box primitive with:

a) corner: 0,0,0

b) length: 75, width: 100, height: 36

3 Create a elliptical cylinder with:

a) centre: 0,0,36 (remember to enter C for this option)

b) axis endpoint: @20,0

c) length of other axis: @0,35

d) height: –18

4 Rectangular array the elliptical cylinder:

a) 2 rows and 2 columns

b) row distance: 100, column distance: 75

5 Subtract the four cylinders from the box – fig(a)

6 Create another cylinder with:

a) centre: 0,50,18

b) radius: 10

c) centre of other end option: @75,0,0

7 Subtract the cylinder from the composite – fig(b)

8 a) Draw a polyline:

start: 0,0 next: 25,30 next: 0,60 next: –25,30 to: close

b) Fillet the polyline with a radius of 6

c) Move the polyline from: 0,0 by: @37.5,20

d) Extrude the polyline for a height of 36 with –8 taper

9 Complete the model by subtracting the extruded polyline from the box composite – fig(c)

10 Save the model as MODR2002\CASTBL

Inquiring into models 243

Figure 37.2 Composite model 5 – a casting block.

11 Menu bar with Format-Units and using the Drawing Units dialogue box alter:

a) Length type: Engineering

b) Precision: 0’-0.00”

c) Insert units: inches

d) pick OK

12 Select the AREA icon from the Inquiry toolbar and:

a) use the object option and pick the composite

b) Area = 29416.67 square in (204.2824 square ft)

13 Select the MASS PROPERTIES icon, pick the composite and:

prompt AutoCAD Text Window

with Mass 155027.84 lb

Volume 155027.84 cu in

respond <RETURN> to the prompt

prompt Write Analysis to a file?<N>

enter Y <R>

prompt Create Mass and Area Properties File dialogue box

with SLIPBL listed from previous exercise

respond 1 enter file name: CASTBL

2 pick Save

14 Investigate

a) The area and mass properties have been ‘calculated’ with the UCS BASE There are

two other UCS saved positions, FRONT and RIGHT Using these saved UCS’s,determine the area and mass/ volume values with engineering units

My values were:

UCS Area(sq in) Mass (lb)/Volume (cu in)

FRONT 29416.67 155029.90RIGHT 29416.67 155027.59These slight variations in mass/volume are due to the way in which AutoCAD 2002performs the various calculations

b) Using the relevant commands, find the area and mass for the composite models

created in previous chapters My values with UCS BASE and decimal units were:

Machine support(31) 81270.75 1022333.68Backing plate(32) 38171.70 98283.83Pipe/flange(33) 190938.19 1305275.35Mass Properties file

When the mass properties command is used with a solid model, the AutoCAD Text dow will display ‘technical’ information about the model including the mass and volume The user has the option of saving this information to a Mass Property file with the

Win-extension mpr As the mass property file is a ‘text file’ it can be opened in any ‘text

editor’ type package

To demonstrate this:

1 Select the Windows Start icon from the Windows bar at the bottom of the screen then

select Programs-Accessories-Notepad and:

prompt Untitled Notepad screen

respond 1 menu bar with File-Open

2 at Look in, scroll and to named folder

3 alter file name to *.mpr then <R>

4 pick SLIPBL

5 pick Open

2 The screen will display the saved material property file for the slip block composite –Fig 37.3(a)

3 This file can then be printed if required

4 Fig 37.3 also displays the material property file for the casting block – fig(b)

5 Exit Notepad to return to AutoCAD

6 Task: can you import the two mpr files into an AutoCAD drawing?

The exercise is now complete

Inquiring into models 245

Figure 37.3 Material properties files from Notepad.

1 Mass properties can be obtained from solid models

2 The mass properties include mass, volume, centroid, radius of gyration etc

3 The mass properties can be saved to an mpr text file

4 AutoCAD 2002 does not support a materials library and hence mass and volume arealways the same, as density is assumed to be 1

Assignment

MACFARAMUS designed many different types of objects including garden walls andpaths It is one of these ‘garden blocks’ that you now have to create as a solid model.The block was one of many used in the design of the famous walled gardens ofCADOPOLIS and the block was made from the mud of the river CLYDEBER on whosebanks CADOPOLIS was built

Activity 22: Garden block of MACFARAMUS

The creation of the garden block is straightforward:

1 Open you template file as normal

2 Using the reference sizes in the activity drawing, create the model from primitives orregions – your choice

3 When the model is complete, save as MODR2002\GARDBL as it will be used in a later

chapter

4 Task

a) when the model is complete, obtain the mass

b) MACFARAMUS obtained a quantity of mud from the banks of the river CLYDEBER

for making the blocks If the mass of this mud was 1000000 units, how many blockscould he make (assuming no waste)

c) I worked out he could create 5748 blocks.

Slicing and sectioning

solid models

Solid models can be sliced (cut) and sectioned relative to:

a) the XY, YZ and ZX coordinate planes

b) three points defined by the user

c) the viewing plane of the current viewpoint

d) user-defined objects

The two commands are very similar in operation and when used:

a) the slice command results in a new composite model This model retains the layer

and colour properties of the original solid

b) the section command adds a 2D region to the model The region is displayed on the

current layer BUT NO HATCHING IS ADDED TO THE REGION.

The two commands will be demonstrated using previously created composite models

Slice example 1 – using the three coordinate planes

1 Open the composite model MODR2002\SLIPBL created in the last chapter

2 Make the Model tab active with UCS BASE and layer Model current with UCS BASE, layer

3 Select the SLICE icon from the Solids toolbar and:

prompt Select objects

respond pick the composite then right-click

prompt Specify first point on slicing plane by [Object/Zaxis/

View/XY/YZ/ZX/3 point]

enter XY <R> – the XY plane option

prompt Specify a point on the XY plane<0,0,0>

enter 0,0,50 <R> – why these coordinates?

prompt Specify a point on desired side of plane or [keep Both sides]

enter B <R> – both sides option

and an XY slicing plane added to the model

4 Erase that part of the model above the slicing plane to give the Fig 38.1(a) effect

5 Undo the erase and slice commands to restore the original model

6 Repeat the SLICE command and:

a) pick the model then right-click

b) enter XY as the slicing plane

c) enter 0,0,50 as a point on the plane

d) enter @0,0,–10 as a point on the desired side of the plane

e) effect is the same as step 3, i.e fig(a)

Chapter 38